I am creating a date file using the following script, i want it to print DATES[] in the file my_dates.txt but it's only printing one date which is 2.0171e+09, that is when i type A(1,1)...i pleading for help?

 for iy = 2005:2017
        yr = num2str(iy);
  for im = 1:12
            if im < 10
               mn = sprintf('0%s',num2str(im));
            else
               mn = num2str(im);
            end
            switch im
              case {1 3 5 7 8 10 12}
                 M_END = 31;
              case {4 6 9 11}
                 M_END = 30;
              otherwise
                 %----------------------------------------------------------
                 % Check whether this is a leap year or not and then assign
                 % the appropriate month end.
                 %----------------------------------------------------------
                 ny = str2num(yr);
                 ly = isequal(floor(ny/4)*4,ny);
                 if ly == 1
                    M_END = 29;
                 else
                    M_END = 28;
                end
            end
   for id = 1:M_END
                if id < 10
                   dy = sprintf('0%s',num2str(id));
                else
                   dy = num2str(id);
                end
                dt = strcat(yr,mn,dy); ndt = str2num(dt);
    
  for ih = 0:6:18
       if ih < 10
           hr = sprintf('0%s',num2str(ih));
       else
           hr = num2str(ih);
           end
            DATES=[];
            Date_STR= strcat(dt,hr);
            Date_num= str2num(Date_STR);

    end
   end
  end
 end
 DATES=vertcat(DATES,[Date_num]);
 fn=sprintf('my_dates.txt');
 fid=fopen(fn,'w');
 fprintf(fid,'%10.2f\n',DATES');
 fclose(fid);

Answer 1

[Are Mjaavatten]

The problem with your file is that you overwrite your Date_num value whenever you calculate a new one. Your DATA variable has no function inside the loop, After the loops, DATA will only replicate Date_num, and is thus superfluous.

Your approach is fine as a Matlab exercise, but for serious work I recommend that you type 'doc datetime' and learn about this and other built-in time and date functions.

Here is version of your code that will work and hopefully do what you want:

Date_num = [];
for iy = 2005:2017
        yr = num2str(iy);
  for im = 1:12
    if im < 10
       mn = sprintf('0%s',num2str(im));
    else
       mn = num2str(im);
    end
    switch im
      case {1 3 5 7 8 10 12}
         M_END = 31;
      case {4 6 9 11}
         M_END = 30;
      otherwise
         %----------------------------------------------------------
         % Check whether this is a leap year or not and then assign
         % the appropriate month end.
         %----------------------------------------------------------
         ny = str2num(yr);
         ly = isequal(floor(ny/4)*4,ny);
         if ly == 1
            M_END = 29;
         else
            M_END = 28;
        end
    end
    for id = 1:M_END
      if id < 10
         dy = sprintf('0%s',num2str(id));
      else
         dy = num2str(id);
      end
      dt = strcat(yr,mn,dy); ndt = str2num(dt);

        for ih = 0:6:18
          if ih < 10
             hr = sprintf('0%s',num2str(ih));
          else
             hr = num2str(ih);
          end
  %         DATES=[];
          Date_STR= strcat(dt,hr);
          Date_num= [Date_num;str2num(Date_STR(end,:))];
        end
      end
    end
  end
  % DATES=vertcat(DATES,[Date_num]);
  fn=sprintf('my_dates.txt');
  fid=fopen(fn,'w');
  fprintf(fid,'%10.2f\n',Date_num);
  fclose(fid);

[siya lolo]

thank you Are Mjaavatten.